Electric crane



May 18,1926. 1,585,351

P. D. IONIDES ELECTRIC 'CRANE Filed July 2. 1924 2 Sheets-Sheet 1 May 18 1926. 1,585,351

P. D. IONIDES ELECTRIC CRANE Filed July 2, 1924 2 Sheets-Sheet 2 Patented May 18, 1926.

UNITED STATES PATENT OFFICE.

PHILIP DENIS IONIDES, OF LONDON, ENGLAND, ASSIGNOR F ONE-HALF TO RANSOMES &; RAPIEB, LIMITED, 0]? IPSWICH, ENGLAND, A BRITISH COMPANY.

ELECTRIC CRANE.

Application filed July 2,

This invention relates to electric cranes particularly those of the self-propelling type having a petrol or other internal combustion engine as the prime mover.

In most, petrol electric systems the petrol engine drives a dynamo electric generator which supplies current to motors furnished with controllers, rheostats, etc. so that most of the regulation of the motors i'srelectrical and is carried out between the generator and the motors much as if the source of power were from ordinary supply mains. This, whilst satisfactory in some respects, involves more or less complicated and expensive regulating and controlling gear. Y

The object of the present invention is the construction of petrol-electric cranesgenerally and of the runabout type in particular in which the various motions such as hoisting, derricking, travelling etc. can all be readily controlled by simple gear.

To accomplish this according to the present invention the dynamo-electric generator supplies power to two or more motors, for

2 1 driving respectively hoisting and lowering,

travelling, derricking or other mechanism employed in the operation of the crane, the control of the motors, which are preferably series wound, being mainly efi'ected through the accelerator pedal of the petrol engine, whereby the speed and voltage of the dynamo-electric generator is varied as may be required according to the speed at which it is desired to operate the motors. The control.

is thus somewhat analogous to that of a pet'- rol mechanically driven car and complicated controllers are dispensed with.

Preferably four motors are provided, two of which drive travelling mechanism while the other two drive respectively hoisting and lowering mechanism and derricking mechanism. the motors each being controlled by a simple form of switch having forward, reverse andneutral positions. The engine is provided with a governor which ensures the engine running at such a moderate speed when the accelerator pedal is not being operated that the voltage developed by the generator is sufliciently low to allow of the motors being thrown directly into circuit without undue disturbance or shock.

The switches for throwing the motors into 1924. Serial No. 723,809.

circuit are preferably arranged in one casing and interlocking mechanism is provided so that the motors cannot be thrown into circuit when the accelerator pedal is in operation. This interlocking arrangement is, however, so constructed that the switches can be moved into their neutral position to throw the motors out of circuit at any posi-- tion of the accelerator pedal.

The petrol engine employed is preferably of the general type used on motors cars and is capable of rapid acceleration and deceler ation so that additional motors can be switched in and brought up to speed quickly.

As stated above, the motors are preferably of the series wound type and, if the governed speed of the engine is such that the generator gives say 50 volts when driven at that speed, the motors may be wound for say 250 volts. The generator is conveniently coupled direct to the petrol or like engine and is arranged to give 250 volts when running with the accelerator pedal fully down. Intermediate voltages may be obtained by. suitable positions of the pedal.

When say one motor is being driven and another is switched in, the effect on the first motor will simply be to slow it up momentarily until the engine has been accelerated, the torque remaining substantially constant.

Circumstances, however, may arise in cording to this invention is illustrated diagrammatically by way of example in the accompanying drawings, in which Figure 1 shows the general arrangement of the interlock between the motor switches and the accelerator pedal as well as the means for automatically weakening the generator field to prevent stalling of the engine.

Figure '2 is a plan view of part of the throttle valve control.

Figure 3 is a side elevation of the crane showing the general dispositioh of the various parts of the operatlng mechanism.

Figure 4 is a plan view of the construction shown in Figure 3 but with the jib and its supports removed for the sake of clearness.

Figure 5 is a diagram showing the general arrangement of circuits.

In the construction illustrated in Figures 3 and 4 the crane truck 1 is supported at three points constituted by two side wheels 2, and by a pair of wheels 3 forming what may be termed a caster 4. A petrol eng1ne 5 is mounted centrally on the truck 1 and is directly connected to a dynamo-electric generator 6. This generator supplies power to a motor 7 disposed on one side of the truck and operating the hoisting and lowering drum 8 though a worm and worm wheel 9 and intermediate gearing 10. The generator 6 also supplies power to a motor 11 disposed on the other side of the truck, and operating a drum 12 for derrickmg the 1b 13 through a worm and worm wheel 14 and intermediate gearing 15.. Two motors 16 opcratively connected through suitable gearing 17 to the caster wheels 3 are also supplied with current from the generator 6. The caster 4 is also adapted to be turned about its vertical pivot 18, for example by means of a steering wheel 19 so as to steer or slew the whole crane.

As shown in Figure 5, the motors 7, 11 and 16 are series wound and are connected 1n parallel to the main conductors 20 and 21 of the generator 6 which is shown as of the shunt wound type by means of motor circuits 22, 23 and 24, the main conductors being provided with a main switch 25 and with ampere and volt meters indicated respectively at 26 and 27.

Reversing switches 28, 29 and 30 are arranged in the motor circu ts, and solenoids are disposed in the circuits 22 and 23 of the hoisting and derricking motors, as 1ndicated at 31 and 32, each of these solenolds being arranged to control a brake whereby hoisting, lowering or derricking Wlll be automatically stopped when the motor control-,

ling such operation is thrown out of circuit. Details of these are not shown as they may be of any known form.

The induction pipe 33 of the petrol engine 5 is provided with a throttle valve 34 connected by means of a rod 35 to the accelerator pedal 36. The engine 5 also has a governor. diagrammatically shown at 37, operating on a lever 38, which is pivoted at 39 and is connected at its upper end to a rod 40. The rod 40 is connected to the throttle valve 33 and each of the rods 35 and 40 is slotted, as shown at 41 in Figure 2, so that the throttle valve can be operated by either the accelerator pedal or the governor independently.

The operating levers for the switches 28, 29 and 30 are shown for convenience at 42,

l3 and 44 and are interlocked with the accelera-tor pedal in such a manner that they cannot be moved from their neutral positions except when the accelerator pedal is in its inoperative position. This interlock comprises a frame 45 longitudinally movable in a casing 46 which encloses the switch levers the movement of the frame being in accordance with the movement of the accelerator pedal. The frame 45 has three bridge pieces 47 each carrying near its centre a pair of oppositely disposed spring-controlled stops or catch members 48. The frame 45 is connected by means of a bell crank lever 49 and a rod 50 to the accelerator pedal 36 in such a manner that, when the accelerator pedal is in its inoperative position, the levers 42, 43 and 44 can be moved into and out of their neutral positions without engaging the spring stops 48. When the accelerator pedal is depressed, however, even to quite a small extent, the frame 47 is moved longitudinally so as to bring the spring stops 48 into the paths of the levers 42, 43 and 44. Thus if any lever is in its neutral position it will be retained in such position between the two spring stops, as shown in Figure 1, and cannot be moved into its forward or reverse position until the accelerator pedal is released. The stops 48 are provided with inclined outer surfaces, however, as shown at 51, so that the levers 42, 43 and 44 can be returned to their neutral positions whatever I the position of the accelerator pedal. Any

tion while the accelerator pedal is depressed will engage the inclined outer surface 51 of the required stop 48 and will force the stop in, the stop springing out again when the lever has passed over it so as to prevent any return movement of the lever until the accelera'tor pedal is released. It will thus be seen that a motor. cannot be switched into circuit except when the accelerator pedal is in its inoperative position but that any motor can be switched out of circuit whatever the position of the accelerator.

The two slotted rods 35 and 40 controlling the throttle are joined at 52 and 53 by a link 54 whose central point is connected by means of a rod 55 to the lowerhend of the arm 56 pivoted at 57 of a rheostat 58. The rheostat is adapted to vary the strength of the generator field in the usual manner.

Ordinarily the link 52 turns about its central point.'s ince the depression of-tl1e accelerator pedal is followed almost im-' mediately by an increase in the speed of the engine, so that, in this case, the arm 56 of the rheostat is not moved. lVhen an overload occurs, however, such as might be liable to stall the engine, and the rods 35 and 40 are both operated to open the throttle, the link 54 is moved bodily and the rheostat arm 56 moved so as to weaken the lield of the generator and reduce the load temporarily. A similar movement of the rheosta-t arm 56 will be brought about if the accelerator pedal is depressed and the engine does not speed up or if the engine speed decreases without movement of the accelerator pedal. ln any one of such circumstances stalling of the engine is prevented.

The arrangement shown diagrammatically in the drawings and described above is given by way of example only and the details of construction may be varied without departing from the spirit of the invention. F or instance the interlocking of the motor switches might be brought about electrically by means of contact arms on the accelerator rod controlling gaps in solenoid or relav circuits. Again the weakening of the field of the generator might be brought about by providing contacts on the accelerator and governor rods so disposed that when both rods are moved to open the throttle a gap in a circuit is closed and an electromagnet or solenoid energized to throw into the field circuit an additional resistance.

\Vhat I claim as my invention and desire to secure-by Letters 'Patent is 1. In a motor control system the combination of an internal combustion engine,,a

dynamo-electric generator adapted to be driven thereby, a plurality of electric motors deriving their current from the generator.

a reversing switch in each motor circuit, a throttle valve controlling the speed of the internal combustion engine, an accelerator operating the throttle valve, and an interlock between the accelerator and the switches such thatno circuit can be closed when the accelerator is in operation.

2. In a motor control system the combination of an internal combustion engine, a dynamo-electric generator adapted to be driven thereby, a plurality of series-wound electric motors deriving their current from the generator, a reversing switch in each motor circuit, a throttle valve controlling the speed of the internal combustion engine, an accelerator operating the throttle valve, and an interlock between the accelerator and the switches such that no circuit can be closed when the accelerator is in operation.

3. In a motor control system the combi-- nation of an internal combustion engine, a dynamo-electric generator adapted to be driven thereby, a plurality of electric motors deriving their current from the generator,

.a reversing switch in each motor circuit, a

, throttle valve controlling the speed of the that no circuit can be closed when the ac-- celerator IS in .operatlon, and a governor internal combustion engine, an-accelerator operating the throttle valve, an lnterlock between the acceleratorand the switches such controlling the throttle valve so that when the accelerator is in its inoperative position the speed of the internal combustion engine will be such that the switches can be thrown directly into circuit without undue shock to the motors or to the mechanisms driven thereby.

4. In a motor-control system the combination of an internal combustion engine, a dynamo-electric generator adapted to be driven thereby, a plurality of series-wound electric motors deriving their current from the generator, a reversing switch in each motor circuit, a throttle valve controlling the speed of the internal combustion engine, an accelerator operating the throttle valve, an interlock between the accelerator and the switches such that no circuit can be closed when the accelerator is in operation, and a governor cont-rolling the throttle valve so that when the accelerator is in its inoperative position thespeed of the internal combustion engine will be such that the switches can be thrown directly into circuit without undue shock to the motors or to the mechanisms driven thereby.

5. In a motor control system the combination of an internal combustion engine, a dyhamo-electric generator adapted to be driven thereby, a plurality of electric motors derivin their current brom the generator, a switc in each motor circuit, a throttle valve controlling. the speed of the internal combustion engine, an accelerator controlling the throttle valve, a governor also controlling the throttle valve independently of the accelerator, a rheostat for varying the strength of the shunt field of the generator, and an interconnection between the shunt field rheostat, the accelerator and the governor such that if the engine speed does not vary in accordance with the movement of the accelerator the strength of the shunt field will be varied to prevent stalling of the engine.

6. In a motor control system the combination of an internal combustion engine, a dynamo-electric generator adapted to be driven thereby, a plurality of electric motors deriving their current from the generator, a reverslng switch 1n each motor circuit, a

"ently of the accelerator, a rheostat for varying the strength of the shunt field of the generator, and an interconnection between the shunt field rheostat, the accelerator and the governor. such that if the engine speed does not vary in accordance with the movement of the accelerator the strength of the shunt field will be varied to the engine.

7. In a motor control system the combinaprevent stalling of -tion of an internal combustion engine, a

dynamo-electric generator adapted to be driven thereby, a plurality of electric motors deriving their current from the generator,

.afiswitch in each motor circuit, a throttle valve controlling the speed of the internal combustion engine, an accelerator controlling the 'throttle valve, a governor also controlling the throttle valve independently of the accelerator, a rheostat for varying the strength of the shunt field of the generator, and an interconnection between the shunt field rheostat, the accelerator, the governor and the switches, such that if the engine speed does not vary in accordance with the movement of the accelerator the strength of the shunt field will be varied to prevent stalling of the engine while the switches cannot be thrown into circuit when the accelerator is in operation.

8. In a motor control system the combination of an internal combustion engine, a dynamo-electric generator adapted to be driven thereby, a plurality of electric motors deriving their current from the generator, a reversing switch in each motor circuit. a throttle valve controlling the speed of the internal combustion engine. an accelerator controlling the throttle valve, a governor also controlling the throttle valve independently of the accelerator, a rheostat for varying the strength of the shunt field of the generator, and an interconnection between the shunt field rheostat, the accelerator, the governor and the switches, such that if the engine speed does not vary in accordance with the movement of the accelerator the strength of the shunt field will be varied to prevent stalling of the engine while the switches cannot be thrown into circuit when the accelerator is in operation.

9. In a motor control system the combination of an internal combustion engine, a dynamo-electric generator adapted to be driven thereby, a plurality of series-wound electric motors deriving their current from the generator, a switch in each motor circuit, a throttle valve controlling the internal combustion engine, an accelerator controlling the throttle valve, a governor also controlling the throttle valve independently of the accelerator, a rheostat for varying the strength of the shunt field of the generator, and an interconnection between the shunt field rheostat, the accelerator and the governor such that if the engine speed does not vary in accordance with the movement of the accelerator the strength of the shunt field will be varied to prevent stalling of the engine.

In testimony whereof I have signed my name to this specification.

PHILIP DENIS IONIDES. 

